Thoughts of an eighth grade math teacher

Monthly Archives: October 2014

Yesterday I posted about my adaptation of the In-N-Out Burger lesson by Robert Kaplinsky. Today I’m posting to give a few updates. The thing about having your students share their questions about a lesson, is that sometimes they ask really good questions that start you wondering. Which then leads to 9 pm trips to the local In-N-Out burger to find answers.

One of my students asked me, “How do they make any money? That is so cheap!” This got me thinking, “Are these prices really accurate?” I pulled up the photos and realized something:

That 100×100 burger was purchased in 2004! Which means that this menu was probably from 2004 too:

There’s no way the prices have stayed the same for 10 years!

On my way home from my brother’s house last night, I stopped by the local In-N-Out to snap a photo of their current menu. I was correct:

Darn inflation! It’s a killer!

I was holding my phone up and trying to get it zoomed in and focused when I heard a man behind me say, “They’re not THAT good.” I turned to him and replied, “Oh, no, I’m not buying anything. I’m a math teacher,” as though this was the most rational explanation in the world for my strange behavior. He nodded and moved ahead of me to place his order. I’ve decided that I need to start using “I’m a junior high math teacher” as my get-out-of-jail-free card more often.

After I took my picture, I was walking out the door to leave, when I thought, “Wait, I have more questions, they’re not very busy, and I’d like some answers.” My ultimate goal was to get a copy of the receipt for the 2014 cost of a 100×100 burger, without actually having to buy one of course. I walked up to the girl at the counter and started explaining it to her. She said, “Well, I could just ring up 50 double-doubles, would that work?” She also tried ringing up 100 cheeseburgers. (Note to self – I’m totally going to use this as an example to discuss proportional reasoning and when it doesn’t work with my students.) I finally had to pull out the picture on my phone to show her what the 100×100 looked like. Her disgusted reaction to the picture was pretty great. It took a little creativity, but she figured out how to ring it up by charging me for one cheeseburger, adding 99 patties and 99 slices of cheese. Here’s the total:

This was pretty good, but I still would have liked it printed out. She fetched the manager to see if it was possible. I found out they can’t print it unless you actually buy it, which I was not about to do, so my picture of the register will have to suffice. I took this opportunity to get an answer to one of the other questions my students had posed: Can you actually order a 100×100 burger? Turns out you can’t. Four patties and six slices of cheese is the biggest they’ll make, at least at the Centerville, Utah In-N-Out. What a let-down! Not that I want to order one. Ever! But it was nice imagining that you could. When I told my classes today, you’d have thought I’d just informed them there was no Santa Clause from the way they reacted.

After I got my picture and thanked the In-N-Out people profusely, I left. I didn’t even order anything! I wasn’t hungry. But sometime later this week I’ll go back and order a cheeseburger and maybe I’ll even splurge on a shake. And I’ll give them a thank-you card.

Here’s the link to the updated version of the powerpoint. I included the menus and total prices from both 2004 and 2014. I also updated my student handout to include questions for the 2014 prices, for the weight, and for the calories.

And before I end, I have a funny story to tell about how this lesson went down in class yesterday. Following Hedge’s lead, I decided to have my students start off by describing an In-N-Out Cheeseburger. Like Hedge, when my students commented that there was a bun, I asked them “Just one bun” and they responded “No there are two buns.” “Are they the same?” I asked. “No, one is flat and one is rounded.” Yea, things started getting weirdly awkward pretty quickly, especially when we students started talking about whether it was better to have flat buns or round buns. After students had been working for a while, I picked a random student and had him tell me his calculated price for the 100X100. It was something way off, so I asked him to explain how he’d arrived at that response. Here’s what he did: 0.90*100 + 0.85*100. When I asked him why he’d done that, he responded, “Because apparently I really like buns.” I laughed pretty hard and then grabbed a marker and wrote it on my quote wall. He was so proud. (Some students care more about making it onto my quote wall than they do about their grade.)